| 1 | /* Modified code from http://tldp.org/HOWTO/MIDI-HOWTO-9.html |
| 2 | * This will print ALSA-Seq (MIDI) events to stdout for further processing eg.: in Arduino |
| 3 | */ |
| 4 | |
| 5 | #include <stdio.h> |
| 6 | #include <stdlib.h> |
| 7 | #include <unistd.h> |
| 8 | #include <alsa/asoundlib.h> |
| 9 | |
| 10 | #define MIDI_NOTE_OFF 128 |
| 11 | #define MIDI_NOTE_ON 144 |
| 12 | #define MIDI_CONTROL 176 |
| 13 | #define MIDI_PITCH_BEND 224 |
| 14 | #define MIDI_FORMAT "%c%c%c" |
| 15 | #define MIDI_FORMAT_ERR "%d:%d:%d\n" |
| 16 | |
| 17 | snd_seq_t *open_seq(); |
| 18 | void midi_action(snd_seq_t *seq_handle); |
| 19 | |
| 20 | snd_seq_t *open_seq() { |
| 21 | |
| 22 | snd_seq_t *seq_handle; |
| 23 | int portid; |
| 24 | |
| 25 | if (snd_seq_open(&seq_handle, "hw", SND_SEQ_OPEN_DUPLEX, 0) < 0) { |
| 26 | fprintf(stderr, "Error opening ALSA sequencer.\n"); |
| 27 | exit(1); |
| 28 | } |
| 29 | snd_seq_set_client_name(seq_handle, "ALSA Sequencer Pipe"); |
| 30 | if ((portid = snd_seq_create_simple_port(seq_handle, "ALSA Sequencer Pipe", |
| 31 | SND_SEQ_PORT_CAP_WRITE|SND_SEQ_PORT_CAP_SUBS_WRITE, |
| 32 | SND_SEQ_PORT_TYPE_APPLICATION)) < 0) { |
| 33 | fprintf(stderr, "Error creating sequencer port.\n"); |
| 34 | exit(1); |
| 35 | } |
| 36 | return(seq_handle); |
| 37 | } |
| 38 | |
| 39 | void midi_action(snd_seq_t *seq_handle) { |
| 40 | |
| 41 | snd_seq_event_t *ev; |
| 42 | |
| 43 | do { |
| 44 | snd_seq_event_input(seq_handle, &ev); |
| 45 | switch (ev->type) { |
| 46 | case SND_SEQ_EVENT_CONTROLLER: |
| 47 | printf(MIDI_FORMAT, MIDI_CONTROL, ev->data.control.channel, ev->data.control.value); |
| 48 | break; |
| 49 | case SND_SEQ_EVENT_PITCHBEND: |
| 50 | printf(MIDI_FORMAT, MIDI_PITCH_BEND, ev->data.control.channel, ev->data.control.value); |
| 51 | break; |
| 52 | case SND_SEQ_EVENT_NOTEON: |
| 53 | printf(MIDI_FORMAT, MIDI_NOTE_ON, ev->data.control.channel, ev->data.note.note); |
| 54 | break; |
| 55 | case SND_SEQ_EVENT_NOTEOFF: |
| 56 | printf(MIDI_FORMAT, MIDI_NOTE_OFF, ev->data.control.channel, ev->data.note.note); |
| 57 | break; |
| 58 | } |
| 59 | fflush(stdout); fflush(stderr); |
| 60 | snd_seq_free_event(ev); |
| 61 | } while (snd_seq_event_input_pending(seq_handle, 0) > 0); |
| 62 | } |
| 63 | |
| 64 | int main(int argc, char *argv[]) { |
| 65 | |
| 66 | snd_seq_t *seq_handle; |
| 67 | int npfd; |
| 68 | struct pollfd *pfd; |
| 69 | |
| 70 | seq_handle = open_seq(); |
| 71 | npfd = snd_seq_poll_descriptors_count(seq_handle, POLLIN); |
| 72 | pfd = (struct pollfd *)alloca(npfd * sizeof(struct pollfd)); |
| 73 | snd_seq_poll_descriptors(seq_handle, pfd, npfd, POLLIN); |
| 74 | |
| 75 | fprintf(stderr, "COMMAND:CHANNEL:NOTE\nCommands are described on http://www.ec.vanderbilt.edu/computermusic/musc216site/MIDI.Commands.html\n\n"); |
| 76 | while (1) { |
| 77 | if (poll(pfd, npfd, 100000) > 0) { |
| 78 | midi_action(seq_handle); |
| 79 | } |
| 80 | } |
| 81 | } |